To be privately owned
Kölzow Castle

Kölzow Castle in Mecklenburg-Vorpommern, built in the 19th century, is now a privately run estate in the Vorpommern-Rügen region.
History+
The construction of Kölzow Castle took place around 1850. The builders were members of the von Prollius family, who erected the new castle on a site where older manor buildings of the von der Lühe family had previously stood. In 1925, the castle gained significance when it became the summer residence of Prince Friedrich Sigismund of Prussia. It remained in the possession of the Prussian family until 1945. After the end of World War II, the owners were dispossessed and expelled as part of the communist land reform.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Roland Neubert, Halle (Saale)
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 54.1039, 12.5421